1. Field of the Invention
This application relates to the commercial processing of corn fiber hulls, and, in particular, to the production of a water soluble corn fiber composition. The water soluble corn fiber composition may be used in food applications as a non-caloric additive or filler or may be used for non-food uses.
2. Description of the Background Art
The water soluble fiber extract from the hulls of corn kernels can serve as a non-caloric additive for food and non-food uses. Methods of extracting the hemicellulosic portion of the corn fiber are well known in the prior art. In particular, well known prior art methods utilize a multi-step process starting with an alkaline extraction of the corn fiber hemicellulose gum fraction as a whole. The processing of the corn fiber by alkaline extraction utilizes hydrogen peroxide, alkali, protease enzyme, and/or solvents to extract the hemicellulose gum. These methods are expensive because of the multiple steps and materials needed. Therefore, it is desirable to develop an economical process utilizing fewer steps and materials.
U.S. Pat. No. 4,038,481 discloses a method of treating corn hulls with alkali to hydrolyze the corn hulls to effect liberation of the hemicellulose fraction.
U.S. Pat. No. 4,957,599 discloses a process for converting nonwoody lignocellulosic substrates into products digestible by ruminants and ingestible by humans by forming a slurry of the substrate with an aqueous alkali for wetting of the substrate and subsequently forming a slurry of the wetted substrate in an alkaline peroxide solution to expose the hemicellulose.
U.S. Pat. No. 5,264,568 discloses a process for preparing a pyrodextrin comprising heating starch in the presence of hydrochloric acid, dissolving the pyrodextrin in water, adjusting the aqueous solution of the pyrodextrin to a pH of from 7.0 to 8.5, pre-hydrolyzing the pH adjusted solution with alpha-amylase produced by Bacillus licheniformis to obtain a hydrolysate, adjusting the hydrolysate to a pH of from 5.5 to 6.5, hydrolyzing the pH adjusted hydrolysate with alpha-amylase, adjusting the hydrolysate to a pH of 4.0 to 5.0, autoclaving the resulting hydrolysate, hydrolyzing the autoclaved hydrolysate with the alpha-amylase, adjusting the hydrolysate to a pH of 4 to 5, and autoclaving the resulting hydrolysate.
U.S. Pat. No. 5,430,141 discloses a process of preparing low calorie dextrin comprising the steps of heating corn starch in the presence of mineral acid to prepare pyrodextrin, hydrolyzing the pyrodextrin with alpha-amylase, adding an organic solvent such as ethanol to the hydrolyzed pyrodextrin and recovering low calorie pyrodextrin from the solvent.
U.S. Pat. No. 6,147,206 discloses a process for the preparation of corn fiber gum comprising mixing corn fiber with an alkaline solution to form a slurry and extract hemicellulose, treating the slurry with hydrogen peroxide at a pH of 10 to 12.5, and separating out the insoluble fractions from the corn fiber slurry to yield corn fiber gum in solution.
In spite of this background art, there remains a very real and substantial need for an economical process for extracting the water-soluble portion of corn fiber hulls to yield a water-soluble non-caloric corn fiber that is useful as an additive to animal feed, ingestible for human food consumption, and for non-food uses such as an ingredient or filler in a pharmaceutical composition.